<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子标签</title>
    <style>
        div {
            border: 1px solid red;
        }

        .div1 {
            width: 200px;
            height: 200px;
        }
        .div2 {
            width: 100px;
            height: 100px;
            margin: 50px;
        }
    </style>
</head>
<body>
<div class="div1">
    <div class="div2"></div>
</div>

</body>
</html>